To reduce the loss torque of a motor by allowing the subject steel sheet to contain a specified compsn. of C, Si, Al, S, Mn, P and N, and the balance substantial Fe.
This steel sheet contains, by weight, ≤0.005% C, ≤2.0% Si, >1.0 to 3.5% Al, ≤0.02% S, 0.05 to 1.5% Mn, ≤0.2% P and ≤0.005% N, and the balance substantial Fe. In the compositional elements, by controlling the contents of Al and S to the above ranges in particular, the hysteresis loss of the steel sheet can remarkably be reduced, so that the loss torque of a motor using this steel sheet can be reduced. As for the content of Al, in the case of >1.0%, a ferritic single phase is formed up to high temp., and the crystal grains are coarsened at the time of high temp. annealing, therefore, the hysteresis loss is made low. On the other hand, in the case of >3.5%, the hysteresis loss is not reduced beyond that, and this is defined as the upper limit.
HIURA AKIRA
SAGAWA TAKASHI
ONO YOSHIHIKO
TANAKA YASUSHI
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